Clad sheet for motor vehicle body

Abstract

The subject of the invention is a composite sheet material made of aluminium alloy for motor vehicle body components, in which a cladding sheet is applied to at least one side of a core, the compositions of the core and of the cladding sheet, in weight percentages, being such as below (See table): other elements <0.05 each and 0.15 in total, remainder aluminium. Another subject of the invention is the process for manufacturing said composite sheet material by co-rolling.

1 . Composite aluminum alloy sheet material for motor vehicle body component, wherein a clad sheet, or clad, with a thickness of 5 to 10% of total thickness of the composite material is applied to at least one side of a core, wherein compositions of said clad and said core, as percentages by weight, are as follows: 
       
         
           
                 
                 
                 
                 
                 
                 
                 
                 
                 
               
                     
                     
                 
                     
                   Si 
                   Fe 
                   Cu 
                   Mn 
                   Mg 
                   Cr 
                   Zn 
                   Ti 
                 
                     
                     
                 
                     
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
               
                   Core 
                   1.1-1.3 
                   <0.3 
                   <0.3 
                   0.05-0.3 
                   0.4-0.8 
                   <0.2 
                   <0.3 
                   <0.2 
                 
                   Clad 
                   0.3-0.9 
                   <0.3 
                   <0.3 
                   0.05-0.3 
                   0.15-0.30 
                   <0.2 
                   <0.3 
                   <0.2 
                 
                     
                 
             
                
                
                
               
               
                
               
            
             
                
                
                
               
            
           
         
         other elements <0.05 each and 0.15 in total, remainder being aluminum. 
       
     
     
         2 . Composite sheet material according to  claim 1 , wherein the magnesium content of the core alloy is from 0.4 to 0.7. 
     
     
         3 . Composite sheet material according to  claim 1 , wherein the manganese content of the core and/or clad alloy is from 0.05 to 0.2. 
     
     
         4 . Composite sheet material according to  claim 1 , wherein the copper content of the core is not more than 0.2. 
     
     
         5 . Composite sheet material according to  claim 1 , wherein the silicon content of the clad is from 0.45 to 0.65. 
     
     
         6 . Composite sheet material according to  claim 1 , wherein the magnesium content of the clad is from 0.23 to 0.29. 
     
     
         7 . Composite sheet material according to  claim 1 , wherein the manganese content of the clad is from 0.10 to 0.30. 
     
     
         8 . Composite sheet material according to  claim 1 , wherein the clad has been applied to the core by co-rolling. 
     
     
         9 . Composite sheet material according to  claim 1 , wherein a clad is applied to only one side of the core. 
     
     
         10 . Composite sheet material according to  claim 1 , wherein a clad is applied to both sides of the core. 
     
     
         11 . Composite sheet material according to  claim 1 , wherein said sheet material has a “three-point bending angle” (α 10% ) measured according to standard NF EN ISO 7438, in the T4P temper, or solution hardened, tempered, pre-aged by winding, optionally from 50 to 85° C., and slowly cooled down to room temperature in the coil, of at least 140° after a tensile pre-strain of 10%. 
     
     
         12 . Composite sheet material according to  claim 11 , wherein said “three-point bending angle” (α 10% ), obtained just after a tensile pre-strain of 10%, of at least 140°, is substantially invariable, or optionally shows a change of less than 5°, with waiting time at room temperature after cooling the coil, for a waiting time of up to at least 6 months. 
     
     
         13 . Composite sheet according to  claim 1 , wherein yield strength Rp 0,2 , after solution heat treatment, quenching, pre-aging by winding, from 50 to 85° C., and cooling slowly in the coil down to room temperature, tensile pre-strain of 2%, and paint baking treatment for 20 min at 185° C., is at least 200 MPa and optionally at least 220 MPa. 
     
     
         14 . Composite sheet according to  claim 1 , wherein said sheet has a “three-point bending angle” (α 10% ), measured according to standard NFEN ISO 7438, in T4P temper, or solution heat treated, quenched, pre-aged by winding, from 50 to 85° C., and slowly cooled in coil down to room temperature, of at least 140° after tensile pre-strain of 10%, and further wherein said sheet has a yield strength Rp0,2, after solution heat treatment, quenching, pre-aging by winding, from 50 to 85° C., and slow cooling in the coil down to room temperature, tensile pre-strain of 2%, and paint baking treatment for 20 min. at 185° C., is at least 200 MPa and optionally at least 220 MPa. 
     
     
         15 . Motor vehicle body sheet wherein said motor vehicle sheet is made from the composite sheet material according to  claim 1 . 
     
     
         16 . Motor vehicle body sheet of  claim 15 , wherein said motor vehicle body sheet is a drawn sheet. 
     
     
         17 . Motor vehicle body sheet according to  claim 15 , wherein said motor vehicle body sheet is a hemmed sheet. 
     
     
         18 . Method of manufacturing a composite aluminum alloy sheet material according to  claim 1 , comprising applying a clad sheet by co-rolling onto at least one side of a core, wherein compositions of the core and the clad sheet are, as percentages by weight, as follows: 
       
         
           
                 
                 
                 
                 
                 
                 
                 
                 
                 
               
                     
                     
                 
                     
                   Si 
                   Fe 
                   Cu 
                   Mn 
                   Mg 
                   Cr 
                   Zn 
                   Ti 
                 
                     
                     
                 
                     
                 
                 
                 
                 
                 
                 
                 
                 
                 
                 
               
                   Core 
                   1.1-1.3 
                   <0.3 
                   <0.3 
                   0.05-0.3 
                   0.4-0.8 
                   <0.2 
                   <0.3 
                   <0.2 
                 
                   Clad 
                   0.3-0.9 
                   <0.3 
                   <0.3 
                   0.05-0.3 
                   0.15-0.30 
                   <0.2 
                   <0.3 
                   <0.2 
                 
                     
                 
             
                
                
                
               
               
                
               
            
             
                
                
                
               
            
           
         
         other elements <0.05 each and 0.15 in total, remainder being aluminum.